This project deals with the problem of obtaining accurate and sensitive descriptions of sequences of behavior in time. Traditional behavioral studies have seldom dealt with these questions. In the present study methods of time series analysis are used to quantify and describe behavioral patterns. Ethological observations are made using an event-recorder program run on a laboratory computer. Analysis includes the evaluation of correlograms and power spectra. A comparison of the mating behavior of two species of hamsters has revealed a different pattern in the occurrence of several components of behavior.